The invention generally relates to optimizing charge phasing of a perforating gun.
For purposes of enhancing production from a subterranean formation, a perforating gun typically is lowered down into a wellbore (that extends through the formation), and radially oriented shaped charges (of the perforating gun) are detonated to form perforations in the formation. Typically, specified parameters called a shot density and a phasing (described below) control the number of shaped charges of the gun and the distances between the shaped charges. If the spacing between two adjacent perforations near the sandface is too small, then a portion of the formation (called a bridge) that is located between the adjacent perforations may fail and permit communication between the perforations. This bridge failure may cause disaggregated sand to be produced through the perforations.
As an example, referring to FIG. 1, a perforating gun 20 includes shaped charges 10 (shaped charges 10a, 10b and 10c, as examples) that extend around a central axis of the gun 20 in a helical, or spiral, pattern. Each shaped charge 10 points radially outwardly toward a well casing 12, and adjacent shaped charges 10 in the spiral pattern are radially separated by a phase angle of 135xc2x0 (as an example), i.e., the phasing of the shaped charges 10 is 135xc2x0.
In one embodiment, a method includes arranging shaped charges in a perforating gun to produce perforation holes in a helical pattern that is defined in part by a phase angle; and choosing four adjacent perforation holes to be created that are adjacent nearest neighbors. The distances are determined between three of the four adjacent perforation holes to be created. A standard deviation is minimized between the three adjacent perforation holes. The phase angle is set based on the minimization.